Calcitonin gene-related peptide increase in the rat spinal dorsal horn and dorsal column nucleus following peripheral nerve injury: up-regulation in a subpopulation of primary afferent sensory neurons.
Calcitonin gene-related peptide in sensory primary afferent neurons has an excitatory effect on postsynaptic neurons and potentiates the effect of substance P in the rat spinal dorsal horn. It has been established that calcitonin gene-related peptide expression in dorsal root ganglion neurons is depressed, and the effect of calcitonin gene-related peptide on dorsal horn neurons is attenuated, following peripheral nerve injury. We report here that a subpopulation of injured dorsal root ganglion neurons show increased expression of calcitonin gene-related peptide. Using in situ hybridization and the retrograde tracer, FluoroGold, we detected an increased number of medium- to large-sized rat dorsal root ganglion neurons projecting to the gracile nucleus that expressed alpha-calcitonin gene-related peptide messenger RNA following spinal nerve transection. Immunohistochemistry revealed a significant increase in calcitonin gene-related peptide immunoreactivity in the gracile nucleus and in laminae III-IV of the spinal dorsal horn. These results indicate that a subpopulation of dorsal root ganglion neurons express alpha-calcitonin gene-related peptide messenger RNA in response to peripheral nerve injury, and transport this peptide to the gracile nucleus and to laminae III-IV of the spinal dorsal horn. The increase of the excitatory neuropeptide, calcitonin gene-related peptide, in sites of primary afferent termination may affect the excitability of postsynaptic neurons, and have a role in neuronal plasticity following peripheral nerve injury.
Miki
K
K
Department of Anatomy and Neuroscience, Hyogo College of Medicine, Nishinomiya, Japan.
Fukuoka
T
T
Tokunaga
A
A
Noguchi
K
K
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000096:biosynthesis / Q000378:metabolism*; D005456:Fluorescent Dyes; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D009475:Neurons, Afferent / Q000378:metabolism / Q000502:physiology*; D017933:Peripheral Nervous System / Q000293:injuries*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000378:metabolism*; D013266:Stilbamidines; D015854:Up-Regulation / Q000502:physiology*
C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D005456:Fluorescent Dyes; D013266:Stilbamidines; D015740:Calcitonin Gene-Related Peptide